Processing photographic materials and processing system therefor

ABSTRACT

A process for the processing of an imagewise exposed photographic material which has been subjected to development and bleach-fixing comprises a plurality of sequential washing steps and where a stain reducing agent is employed wherein the photographic material is contacted with an effective amount of the stain reducing agent in the wash liquid in a first washing step and the photographic material is subjected to a following washing step to remove the stain reducing agent. The process may employ a plurality of wash tanks in which the developed material is washed sequentially and the stain reducing agent is present in the wash liquid in a first wash tank and removed from the photographic material by the wash liquid in one or more following wash tanks. The temperature of wash liquids in the tanks is preferably within the range 40 to 70° C., preferably 45 to 65° C. 
     The invention includes a photoprocessor system for the processing of photographic materials for example film or paper comprising: a development tank associated with a bleach-fix tank which is associated with a first of a plurality of wash tanks connected in series and wherein there is provided a reservoir for a stain reducing agent and means for supplying the stain reducing agent to the first wash tank.

FIELD OF THE INVENTION

This invention relates to the processing of photographic materials andto a processing system therefor.

BACKGROUND OF THE INVENTION

In the processing of photographic materials such as paper and film ithas sometimes been found that a stain appears in the developed material.The staining is due primarily to retained sensitising dye. The risk of astaining is greater in the case of rapid processes which have beendeveloped employing short cycle times and in which the durations of theindividual stages of development, bleach-fix and wash arecorrespondingly short.

PROBLEM TO BE SOLVED BY THE INVENTION

Certain chemical compounds, known in the art as stain reducing agents,have been previously used for reducing staining and it has been proposedto add a stain reducing agent to the developer liquid. However it hasbeen found that when a short wash time is employed, for example about 15seconds, that a stain is produced on the developed material. Theinventor of the present invention has found that when the concentrationof stain reducing agent in the developer solution is increased, thestain is initially reduced but after about 4 weeks is found to increasesubstantially. Furthermore, they have found that stain reducing agentsare not very soluble in the developer solution and tend to precipitate.The stain reducing agent can be added to the bleach-fix solution withthe effect that the stain is reduced but here the stain reducing agentis even more prone to precipitate than in the developer. If the stainreducing agent is added to wash water or stabiliser-replenisher it issoluble to a high degree and prevents stain initially but is present inthe entire wash and thus retained in the photographic material.

A solution to this problem has now been invented in which the stainreducing agent is added to the first wash or stabiliser tank only andnot to subsequent wash or stabiliser tanks. Stain reducing agent is moresoluble in this solution than in the developer or bleach-fix and hencethe amount in solution is enough to prevent staining. In a preferredembodiment of the invention the wash or stabiliser tanks are run atelevated temperature sufficient to remove the stain reducing agent fromthe photographic material.

SUMMARY OF THE INVENTION

According to the present invention there is provided a process for theprocessing of an imagewise exposed photographic material which has beensubjected to development and bleach-fixing which process comprises aplurality of sequential washing steps and where a stain reducing agentis employed wherein the photographic material is contacted with aneffective amount of the stain reducing agent in the wash liquid in afirst washing step and the photographic material is subjected to afollowing washing step to remove the stain reducing agent.

ADVANTAGEOUS EFFECT OF THE INVENTION

The advantage of the invention is that staining is kept to a low level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the effect on stain level of an increase in the washtemperature.

FIG. 2 shows a typical arrangement of developer, bleach-fix and washtanks in a minilab photoprocessor system.

DETAILED DESCRIPTION OF THE INVENTION

References to a wash liquid being free of stain reducing agent mean thatno stain reducing agent is present apart from that which may be carriedover by the photographic material from the previous tank.

The term wash liquid is intended to include stabilising liquid. Theinvention is particularly applicable to rapid processing using shortcycle times and correspondingly short individual steps.

The invention is suitable for use in small photoprocessors which havebecome known as minilabs. These usually have a total of four wash orstabiliser tanks. When such a processor is employed the stain reducingagent will normally be added to the wash liquid in the first tank onlyand the wash liquid in subsequent tanks will be free of stain reducingagent apart from contamination by carry over. The stain reducing agentwill select from those that remove sensitising dye and are removable bywater washing so that neither are retained in the developed photographicmaterial. Suitable agents include those containing a diamino stilbenestructure. Suitable stain reducing agents are disclosed in U.S. Pat. No5,395,742

Suitable concentrations of stain reducing agent in the wash liquid areup to about 12 g/l preferably from about 1 to about 9 g/l.

Suitable stain reducing agents are those sold under the trade namesPhorwite REU, Tinopal SFP and Uvitex MST 300. Phorwite is preferred.

Phorwite has the chemical formula:

According to another aspect of the invention a photoprocessor system forthe processing of photographic materials, for example film or papercomprises: a development tank (2) associated with a bleach-fix tank (4)which is associated with a first of a plurality of wash tanks (6, 8, 10and 12) connected in series and wherein there is provided a reservoir(14) for a stain reducing agent and means (16) for supplying the stainreducing agent to the first wash tank (6).

The photoprocessor may be a small photoprocessor known in the art as aminilab. In this case it is preferred that the stain reducing agent ispresent in the wash liquid in the first wash tank whilst the wash liquidin the subsequent wash tanks (usually three in number as there areusually four wash tanks in total) contains no stain reducing agent apartfrom any carry over.

Referring to FIG. 2 minilab is indicated generally by reference numeral1. Photographic paper which moves in a direction of from left to rightas indicated by the arrow is passed through the developer liquid in tank2. Tank 2 is replenished as indicated by the arrow and letter R. Thepaper is then passed through the bleach-fix liquid in tank 4. Tank 4 isalso replenished as indicated by the arrow and letter R.

The liquid levels in tanks 2 and 4 are maintained constant by overflow(not shown).

The paper is then passed through the wash liquid in the wash tank 6which is the first of four wash tanks 6, 8, 10 and 12.

The stain reducing agent is added to the wash liquid in tank 6 and willbe replenished to maintain the concentration at the desired level in therange 2 to 12 g/l. The liquid level in tank 6 is maintained constant byreplenishment indicated by the letter R and by overflow (not shown). Thewash liquid in tank 12 is replenished as indicated by the letter R withwater or stabiliser free of stain reducing agent and the levelmaintained constant by overflow into tank 10 which in turn overflowsinto tank 8 which overflows into tank 6. Thus the direction of thephotographic paper is countercurrent to the flow of liquid in the washtanks. Stain reducing agent on the paper as a result of passage throughtank 6 is removed in the subsequent washing tanks 8, 10 and 12.

The invention is illustrated by the following Examples.

EXAMPLE 1

In this Example a short process cycle as shown in Table 1 was run in asinkline in which the first wash tank contained either water as acomparison or Phorwite REU.

TABLE 1 short process cycle Temperature Develop 15 seconds 40° C.bleach-fix 15 seconds 40° C. first wash 5 to 20 seconds 37° C. main wash15 seconds 37° C.

Where the developer is Kodak (Registered Trade Mark) Ektacolor SM(Registered Trade Mark) developer, bleach-fix is Kodak Ektacolor SMbleach-fix (pH 6.3). The paper used was Ektacolor Edge 7. The first washstage included a water check and solutions of Phorwite REU at 2 g/l and8 g/l. Phorwite REU is an optical brightener. The reference processcycle is shown in Table 2.

TABLE 2 long process cycle temperature develop 45 seconds 37.8° C.bleach-fix 45 seconds 37.8° C. wash 90 seconds   35° C.

Where the developer is Kodak (Registered Trade Mark) RA-12 developer andthe bleach-fix is Kodak RA-12 bleach-fix. This process gives thereference values for CIELAB stain measurements for Kodak Ektacolor(Registered Trade Mark) Edge 7 paper and these are shown in Table 3.These are the values to be aimed at for the short process cycle.

The results are in Table 3 in terms of CIELAB stain measurements L, a*and b* which were measured in all cases reported herein on a specialarray densitometer with a UV filter in the light source.

TABLE 3 Stain measurements first wash solution total wash strip seeTable first wash time 90 L a* b* ref 2 reference time seconds 90.647−0.007 −1.158 147-1 Water comparison 5 seconds 20 89.703 0.288 0.636147-14 REU (2 g/l) invention 5 20 89.73 0.508 −0.697 147-13 REU (8 g/l)invention 5 20 89.908 0.331 −0.569 147-7 Water comparison 10 25 89.8610.307 0.505 147-15 REU (2 g/l) invention 10 25 89.95 0.270 −0.512 147-8REU (8 g/l) invention 10 25 90.12 0.188 −1.008 147-9 Water comparison 2035 90.135 0.044 −0.547 147-16 REU (2 g/l) invention 20 35 90.087 0.194−1.015 147-10 REU (8 g/l) invention 20 35 90.395 0.034 −1.430

It can be seen from the data in Table 3 that the presence of PhorwiteREU in the first wash tank shows that L and a* are not affected verymuch but they do show a small improvement towards the aim referencevalues. The improvement in b* is much more significant. For the higherlevel of Phorwite b* is better than the reference value for a muchshorter wash time of 35 seconds compared with 90 seconds.

Observation of the paper strips when placed under an ultraviolet lamp(366 nm) showed a small amount of fluorescence for strips with PhorwiteREU in the first wash tank that had a following 15 second wash. Stripsin which the final 15 second wash was omitted showed a strongfluorescence. This indicates that some but not all the Phorwite REU isremoved in the final 15 second wash.

In order to remove any retained Phorwite another experiment was run witha longer final wash of 60 seconds. The data are shown in Table 4.

TABLE 4 Long final wash first wash solution total wash strip see Tablefirst wash time 90 L a* b* ref 2 reference time seconds 90.647 −0.007−1.158 147-3 water comparison 5 seconds 65 90.44 −0.222 −0.916 147-4 REU(8 g/l) invention 5 65 90.635 −0.192 −1.04 147-5 water comparison 10 7090.504 −0.2 −0.81 147-6 REU (8 g/l) invention 10 70 90.605 −0.122 −1.25147-11 water comparison 20 80 90.511 −0.202 −1.158 147-12 REU (8 g/l)invention 20 80 90.701 −0.078 −1.829

It can be seen from Table 4 that even with a long final wash thepresence of Phorwite REU in the first wash tank improves the stainposition relative to the same tank without Phorwite. In addition thefinal stain is better than the reference for a total wash time of 70seconds or more and even at 65 seconds it is very close to the referencevalues.

Examination of the strips under an ultraviolet lamp at 366 nm showedthat there was only very slight fluorescence indicating almost noretained Phorwite in the paper.

Thus it is possible to shorten wash time and obtain a stain position asgood as or better than the reference by using the principle of includingPhorwite REU in the first wash tank but not in the following wash tanks.It is also possible by this method to prevent retained Phorwite REU inthe coating with shorter wash times than the reference process.

This example demonstrates the first benefit of the invention in thatshorter wash times are possible, with no retained Phorwite and freshstain levels equal or better than the reference.

EXAMPLE 2

This experiment demonstrates the benefit of higher temperature washing.

In this example a relatively poor wash condition was deliberately usedto check the effect of wash water temperature on the stain level incolour paper. The process cycle used was as in Table 5.

TABLE 5 short process cycle temperature develop 15 seconds 40° C.bleach-fix (pH 5.4) 15 seconds 40° C. wash 30 seconds 21 to 55° C.

Where the developer is Kodak Ektacolor SM developer, bleach-fix is KodakEktacolor SM bleach-fix (pH 5.2). This condition with the lower pH inthe bleach-fix than used in Example 1 coupled with a 30 second washresults in a worse stain position than the reference values. The paperused was Ektacolor Edge 7.

It can be seen from FIG. 1 that on average b* falls by over one unitwith increase in temperature from 22 to 55° C. This is a significantimprovement in the stain level in the next example temperature increasein the wash is used in combination with Phorwite REU in the first washtank to lower retained Phorwite in the paper.

EXAMPLE 3

According to the invention.

In this example Phorwite REU was present in the first wash tank and themain wash was examined at two different temperatures as shown in theprocess cycle in Table 6.

TABLE 6 short process cycle temperature develop 15 seconds 40° C.bleach-fix 15 seconds 40° C. first wash 5 to 20 seconds 40° C. main wash15 seconds 37 and 56° C.

The results are shown in Table 7.

TABLE 7 Effect of Phorwite and final wash temperature First wash washtotal strip solution temperature first wash wash time L a* b* ref seeTable 2 35 time 90 seconds 90.647 −0.007 −1.158 147-14 REU (2 g/l) 37 5seconds 20 89.729 0.509 −0.697 147-18 REU (2 g/l) 56 5 20 90.2493 0.149−0.964 147-15 REU (2 g/l) 37 10 25 89.95 0.270 −0.512 147-19 REU (2 g/l)56 10 25 90.314 0.086 −0.712 147-17 REU (2 g/l) 37 15 30 90.265 0.097−0.785 147-21 REU (2 g/l) 56 15 30 90.349 0.084 −1.086 147-16 REU (2g/l) 37 20 35 90.087 0.194 −1.015 147-20 REU (2 g/l) 56 20 35 90.3090.076 −1.162

The data in Table 7 shows that the values of L, a* and b* are closer tothe reference values for the final wash with the higher temperature. Inaddition by viewing the strips under an ultraviolet lamp at 366 nm itwas clear that there was some fluorescence for the low temperature washparticularly at short wash times but there was almost no fluorescencefor any of the wash times for the higher temperature wash. These dataindicate that a higher wash temperature lowers stain and in additionprevents retention of Phorwite REU in the paper.

The values of L, a* and b* are very close to the reference values andthus the method described in the invention in which Phorwite REU ispresent only in the first wash tank followed by a main wash which doesnot contain Phorwite REU but is run at a higher temperature can give lowstain levels even for very short wash times.

This example demonstrates the second benefit of the invention wherebyeven shorter wash times than those already demonstrated in example 1 arepossible with stain levels as good as the reference.

EXAMPLE 4

According to the invention.

It has been found that if paper strips processed with short wash timesare left stacked together for a period of time a room temperature,largely without any incident light, the stain level can increase. Thisis particularly noticeable in the b* value and corresponds to anincrease in yellow stain. Some strips (processed by the methodsdescribed in this report) were re-measured after standing for 4 weeks atroom temperature. (22° C.). Some results are shown in Table 8.

TABLE 8 Strips re-measured after 4 weeks first wash first wash totalwash Strip solution time time L a* b* 147-1 water comparison 5 seconds20 seconds 89.703 0.288 0.636 147-1b water re- 5 seconds 20 89.396−0.017 3.468 measured 147-14 REU (2 g/l) invention 5 20 89.73 0.508−0.697 147-14b REU (2 g/l) re- 5 20 89.565 0.188 1.339 measured 147-13REU (8 g/l) invention 5 20 89.908 0.331 −0.569 147-13b REU (8 g/l) re- 520 89.786 0.042 1.453 measured 147-7 water comparison 10 25 89.861 0.3070.505 147-7b water re- 89.691 0.247 1.828 measured 147-15 REU (2 g/l)invention 10 25 89.95 0.270 −0.512 147-15b REU (2 g/l) re- 10 25 89.8440.202 0.388 measured 147-8 REU (8 g/l) invention 10 25 90.12 0.188−1.008 147-8b REU (8 g/l) re- 10 25 90.05 0.101 −0.048 measured 147-9water comparison 20 35 90.135 0.044 −0.547 147-9b water re- 20 35 90.04−0.091 0.524 measured 147-16 REU (2 g/l) invention 20 35 90.087 0.194−1.015 147-16b REU (2 g/l) re- 20 35 90.212 0.124 −0.404 measured 147-10REU (8 g/l) invention 20 35 90.395 0.034 −1.430 147-10b REU (8 g/l) re-20 35 90.385 0.049 −0.909 measured

The data in Table 8 show that after keeping for 4 weeks stain levelshave increased for all strips. In all cases the stain for the watercomparison increases more than the Phorwite example.

This shows the third benefit of the invention in that stain increases onkeeping after short wash times are less if Phorwite REU is present inthe first wash tank. It is desired however to employ the method of theinvention and to further lower the stain increase on keeping and this isshown in the next example.

EXAMPLE 5

According to the invention.

If the final wash is extended as in the example described in table 3,the general stain increase on keeping can be lowered irrespective of themethod. The data are shown in Table 9.

TABLE 9 Strips re-measured after 4 weeks (long final wash) first washfirst wash total wash Strip solution time time L a* b* 147-3 watercomparison 5 seconds 65 90.44 −0.222 −0.916 147-3b water re- 5 65 90.44−0.196 −0.529 measured 147-4 REU (8 g/l) invention 5 65 90.635 −0.192−1.04 147-4b REU (8 g/l) re- 5 65 90.641 −0.150 −0.762 measured 147-5water comparison 10 70 90.504 −0.2 −0.81 147-5b water re- 10 70 90.479−0.160 −0.444 measured 147-6 REU (8 g/l) invention 10 70 90.605 −0.122−1.25 147-6b REU (8 g/l) re- 10 70 90.626 −0.010 −1.101 measured 147-11water comparison 20 80 90.511 −0.202 −1.158 147-11b water re- 20 8090.529 −0.129 −0.997 measured 147-12 REU (8 g/l) invention 20 80 90.701−0.078 −1.829 147-12b REU (8 g/l) re- 20 80 90.759 −0.063 −1.735measured

The data in Table 9 show unexpectedly thst even with longer wash timescompared with those shown in example 1 the benefit of Phorwite in thefirst was tank is still demonstrated. The stain increases on keeping isless for the Phorwite examples and is minimal at the longer times. Thusalthough these wash times are longer than desired they are still shorterthan those used in the reference process.

This shows the fourth benefit of the invention in that shorter washtimes than the reference can be achieved, with no retained Phorwite REUand with minimal stain increase on keeping.

It is however desired to shorten the wash times even more than in theabove example. This is shown in the next example.

EXAMPLE 6

According to the invention.

In this example the use of Phorwite in the first wash tank is combinedwith a following wash at higher temperature (56° C.). The results areshown in Table 10. The strip numbers with the b suffix are there-measured strips.

The b suffix means the strips were re-measured after 4 weeks.

TABLE 10 Effect of Phorwite and final wash temperature re-measuredstrips first wash wash first wash total wash strip solution temperaturetime time L a* b* 147-14 REU (2 g/l) 37 5 seconds 20 89.729 0.509 −0.697147-14b ″ 37 5 20 89.568 0.188 1.339 147-18 REU (2 g/l) 56 5 20 90.24930.149 −0.964 147-18b ″ 56 5 20 90.215 0.095 −0.446 147-15 REU (2 g/l) 3710 25 89.95 0.270 −0.512 137-15b ″ 37 10 25 89.844 0.202 0.389 147-19REU (2 g/l) 56 10 25 90.314 0.086 −0.712 147-19b ″ 56 10 25 90.326 0.086−0.331 147-17 REU (2 g/l) 37 15 30 90.265 0.097 −0.785 147-17b ″ 37 1530 90.053 0.179 −0.470 147-21 REU (2 g/l) 56 15 30 90.349 0.084 −1.086147 21b ″ 56 15 30 90.38 0.206 −0.956 147-16 REU (2 g/l) 37 20 35 90.0870.194 −1.015 147-16b ″ 37 20 35 90.212 0.124 −0.404 147-20 REU (2 g/l)56 20 35 90.309 0.076 −1.162 147-20b ″ 56 20 35 90.343 0.097 −0.996

It can be seen from Table 10 that the higher temperature final wash hasbetter fresh stain values and also lower stain increase after keeping.The stain values for 30 seconds or more total wash are now very close tothe reference values and show almost no increase on keeping. Anexamination of the strips under an ultraviolet lamp at 366 nm showsalmost no fluorescence for the higher temperature cases even at shortwash times. This shows that Phorwite REU is not retained in the paper.

This demonstrates the fifth benefit of the invention in that very shortwash times are possible with low fresh stain, no retained Phorwite REUand minimal increase in stain on keeping.

EXAMPLE 1a

Two other stain reducing agents were compared with Phorwite REU. Thesewere Tinopal SFP and Uvitex MST 300.

These stain reducing agents were dissolved in the first wash at 0, 2 and8 g/l in tap water.

The paper was Ektacolor Edge 7. This paper was about 6 months older thanwhen used for the original experiments with Phorwite REU so the basicstain level was expected to be higher.

TABLE 1a process cycle Temperature develop 14 sec 40° C. blix 14 sec 40°C. first wash 5, 10, 15 sec 40° C. final wash 15 sec 36° C. dry in air

Where the developer is Ektacolor SM tank developer, and the blix isEktacolor SM tank bleach-fix The blix was adjusted to pH of 6.2 beforeuse.

The results are shown in Table 2a are for 2 g/l stain reducing agent andin 3a for 8 g/l stain reducer. In these experiments the first wash was5, 10 or 15 seconds.

The final wash was always 15 seconds. Water was used as the check forthe first wash in each case.

The data shown in Table. 2a show the CIELAB measurements (L, a* andb*)and the red, green and blue (RGB) Dmin density measurements with andwithout a UV filter in the light source. A consistent pattern is clearin that Phorwite lowers b* and B Dmin more than other materials althoughall the stain reducers show an improvement over the water check.

The data in Table 3a are similar to those in Table 2a except that theeffects are greater for the higher level of stain reducer. Phorwite REUconsistently has lower b* and B Dmin values with and without a UV filterthan the other stain reducers although all of them show an improvementover the water check.

TABLE 2a Comparison of stain reducers in first wash (2 g/l) u.v filterno u.v filter D min × 1000 Dmin × 1000 first wash time L a* b* R G B R GB water 5 90.67 −1.25 0.46 110 102 111 95 93 91 Tinopat 5 90.62 −1.270.78 109 104 113 94 94 88 (2 g/l) Uvitex 5 90.60 −1.33 0.64 111 104 11493 94 91 (2 g/l) Phorwite 5 90.43 −1.13 0.02 112 105 110 97 96 88 (2g/l) water 10 90.63 −1.25 0.42 110 104 111 92 93 90 Tinopat 10 90.78−1.16 0.54 107 102 108 90 91 81 (2 g/l) Uvitex 10 90.62 −1.28 0.11 110103 108 93 93 83 (2 g/l) Phorwite 10 90.62 −1.10 −0.4 110 104 103 95 9480 (2 g/l) water 15 90.72 −1.10 0.05 108 102 107 92 92 88 Tinopal 1590.66 −1.09 0.04 108 103 104 94 04 76 (2 g/l) Uvitex 15 90.77 −1.15 0.16108 101 106 91 90 78 (2 g/l) Phorwite 15 90.76 −1.01 −0.4 108 102 101 9394 77 (2 g/l)

TABLE 3a Comparison of stain reducers in first wash u.v filter no u.vfilter D min × 1000 Dmin × 1000 first wash time L a* b* R G B R G Bwater 5 90.67 −1.25 0.46 110 102 111 95 93 91 Tinopal 5 90.54 −0.76 1.06106 106 113 89 98 86 (8 g/l) Uvitex 5 90.56 −1.27 0.68 111 104 113 94 9486 (8 g/l) Phorwite 5 90.65 −1.18 0.15 110 103 106 94 95 81 (8 g/l)water 10 90.63 −1.25 0.42 110 104 111 92 93 90 Tinopal 10 90.6  −1.940.37 108 104 106 92 93 73 (8 g/l) Uvitex 10 90.52 −1.22 0.03 111 104 10894 95 78 (8 g/l) Phorwite 10 90.71 −0.98 −0.3 108 103 102 93 94 74 (8g/l) water 15 90.72 −1.10 0.05 108 102 107 92 92 88 Tinopal 15 90.65−0.99 0.00 108 103 104 93 94 70 (8 g/l) Uvitex 15 90.66 −1.12 −0.03 109103 106 92 93 73 (8 g/l) Phorwite 15 90.69 −0.85 −0.77 109 103 97 92 9367 (8 g/l)

EXAMPLE 2a

In this example the effect of the stain reducers on Dmax is examined andalso the ease with which they wash out of the coating. The strips wereprocessed in the standard Ektacolor SM process and dried. They were thenmeasured for B Dmax (1), immersed in a solution of water or the stainreducing agent at 2 g/l for 15 seconds, dried measured for B Dmax (2)and then washed for 15 seconds, dried, measured for B Dmax(3).

TABLE 4a Effect of stain reducers (2 g/l) on blue Dmax. compound B Dmax1B Dmax2 B Dmax3 water 2.14 2.14 2.14 Tinopal (2 g/l) 2.14 1.99 2.03Uvitex (2 g/l) 2.13 2.00 2.05 Phorwite (2 g/l) 2.14 2.06 2.11

It can be seen that after treatment with the stain reducers there is aloss of B Dmax which is caused by the fluorescence of retained stainreducer, thus it is desired to minimise the loss of B Dmax but also tomaximise the improvement in B dmin also caused by the stain reducer. Inthe case of some stain reducers, particularly Phorwite REU, theimprovement in B Dmin is only partly caused by (a) fluorescence but alsomainly by (b) assisting the removal of retained sensitising dye. Thus animprovement in B Dmin should be obtainable by mechanism (b) by themethod of the invention, this appears to be the case from the data shownabove. In Table 4a the loss in B Dmax (2) is less for Phorwite than theothers. In addition the restoration of B Dmax (3) after a I5 second washis better with Phorwite than the others. In all Phorwite shows only a0.03 loss of B Dmax whereas the others show 0.08 (Uvitex) and 0.11(Tinopal). The data combined with that from Tables 2a and 3a in whichPhorwite shows a significant improvement in B Dmin demonstrates theinvention.

The same experiment was repeated with 8 g/l of stain reducer.

TABLE 5a Effect of stain reducers (8 g/l) on blue Dmax compound B Dmax1B Dmax2 B Dmax3 water 2.13 2.13 2.13 Tinopal (8 g/l) 2.14 1.84 1.96Uvitex (8 g/l) 2.13 1.92 2.00 Phorwite (8 g/l) 2.14 1.94 2.06

Phorwite shows only a 0.08 loss of B Dmax whereas Uvitex shows 0.13 andTinopal 0.18.

Thus the method of the invention is demonstrated in that a reduction inblue Dmin density is obtainable by the inclusion of a stain reducer inthe first wash followed by a completion of the wash without stainreducer. In addition the loss in blue Dmax caused by the retention ofthe stain reducer is minimised. This combination of desired results canbe highlighted by the ratio of the blue Dmax to the blue Dmin as shownin Table 6a.

TABLE 6a ratio of B Dmax/B Dmin compound Dmax/Dmin (2 g/l) Dmax/Dmin (8g/l) water 24.2 24.2 Tinopal 26.7 28.0 Uvitex 26.3 27.3 Phorwite 27.430.7

Here it can be seen that all the stain reducers are beneficial in thefirst wash compared with water which demonstrates the principal of theinvention but also that Phorwite REU is better than the other two.

What is claimed is:
 1. A process for the processing of an imagewiseexposed photographic material which has been subjected to developmentand bleach-fixing which process comprises a plurality of sequentialwashing steps and where a stain reducing agent is employed wherein thephotographic material is contacted with an effective amount of the stainreducing agent in the wash liquid in a first washing step and thephotographic material is subjected to a following washing step to removethe stain reducing agent.
 2. A process as claimed in claim 1 employing aplurality of wash tanks in which the developed material is washedsequentially and wherein the stain reducing agent is present in the washliquid in a first wash tank and removed from the photographic materialby the wash liquid in one or more following wash tanks.
 3. A process asclaimed in claim 1 wherein the temperature of wash liquids is within therange 40 to 70° C.
 4. A process as claimed in claim 1 wherein thephotographic material is subjected to a following washing step to removethe stain reducing agent, the process being a rapid process employing aplurality of washing steps and in which the durations of the individualwashing steps are not greater than 30 seconds.
 5. A process as claimedin claim 1, wherein the stain reducing agent is one containing a diaminostilbene structure.
 6. A process as claimed in claim 1, wherein theconcentration of stain reducing agent in the wash liquid to which it isadded is up to 12 g/l.
 7. A process as claimed in claim 5, wherein theconcentration of stain reducing agent in the wash liquid to which it isadded is from 1.5 to 9 g/l.